No matter who is elected the next president of the United States, he may have a tough time getting his agenda through Congress.

Projections Tuesday show Republicans will hold onto control of the House of Representatives while Democrats will stay in charge of the Senate.

Democrats made key inroads in the Senate, defeating the Republican incumbent in Massachusetts (Senator Scott Brown losing to Democratic challenger Elizabeth Warren), winning the swing state of Virginia, where former Republican governor George Allen conceded to former governor Tim Kaine and holding on in the battleground state of Ohio, where Democratic Senator Sherrod Brown held off a challenge from Republican Josh Mandel.

Democrats also picked up a seat in Indiana, where Representative Joe Donnelly defeated Republican Richard Mourdock. The contest drew national attention after Mourdock made controversial remarks about rape and abortion. Another Republican candidate who made similarly controversial remarks also lost in Missouri (Representative Todd Akin losing to incumbent Democratic Senator Claire McCaskill).

U.S. Sen. Bill Nelson, D-Fla. thanks supporters at a re-election party in Orlando, Florida, Tuesday, Nov. 6, 2012. On his left, is wife Grace Nelson.

Projections also have the Democrats holding onto Florida, where incumbent Bill Nelson defeated Republican Connie Mack and Pennsylvania, while the Republicans lost a seat in Maine to Independent candidate Angus King.

Thirty-three seats in the 100-seat Senate were up for election. Republicans need to gain four seats to take control.

Projections also indicate little will change in the House, with Republicans maintaining their majority as voters in many states re-elected incumbents from both parties. That means Republican Representative John Boehner from the battleground state of Ohio will likely retain his post as House Speaker.

In a statement late Tuesday night, Boehner said Republicans were "humbled" to have been chosen by voters to lead the House and that they would continue to oppose any calls to raise taxes. But he also offered to work with any willing partner in the White House.

All 435 House seats were up for grabs and Democrats would have needed to gain 25 seats to take control.

A number of polls have shown many Americans have been frustrated by what they see as rampant politicking and animosity on the part of lawmakers, seeing little improvement in their day-to-day lives. But their views of lawmakers appeared to improve in the weeks preceding Tuesday's election.

A poll by the Gallup Organization released October 24 found 21 percent of Americans approved of the job Congress was doing, up from 13 percent in September. It was also the highest rating for lawmakers since May 2011.

Gallup says that, going back to 1974, the average job approval rating in Congress has been about 34 percent. Gallup also says most voters think more highly of their own representatives than they do of other members of Congress.